I've done a lot of research because I am also looking to buy one and watched countless youtube videos and decided on the G45.
First, make sure to get a Gen 5 version regardless of which one you chose. There have been notable changes that make the Glock a lot better compared to previous generations due to increased competition in this market. A noticeable difference is the improved trigger that a lot of industry professionals have been mentioning.
Second, you can also consider the G45 which is basically a Glock 19x but in black that was made specifically for LEO.
From all the youtube videos I have seen, everyone has been saying the 19x or G45 handles a lot better than the 17 or the 19. The 19 slide isn't as big meaning the force of it coming back isn't as strong as a 17 while it has the full sized grip of a 17 meaning you can get a better grip on it.
The 19x will only accept certain magazines due to the lip at the mag well however this is easily fixable as you could just sand it down or change the baseplate of magazines you already have.
The G45 doesn't have this lip and will fit all magazines and has front slide serrations that come standard.
As it stands, there is no MOS version of the 19x however there are some guys in Edmonton that can mill the slide to fit a red dot.